Fix set_param in several layers that were rejecting parameters from files with old format.
Merge pull request #32 from genete/param-interpolation

Fix set_param in several layers that were rejecting parameters from file...
Remove unnecessary qualifiers from color.h
Fix float literals in etl::surface
"Unvirtualise" method etl::surface::set_wh(w,h,newdata,pitch)
Remove unused variables from color.cpp
Fix custom isnan macro in color.h and vector.h
Why 'hbiter_pos' never used in advanced_outline.cpp?
Comment unused variables in advanced_outline.cpp
remove unused variables
Commented 'angle' var, which reads from SVG and not used in svg_parser
Removed strange unused code from curveset.cpp
Fix float literals in random_noise.cpp
Fix: returns 'false' instead NULL-pointer in distort.cpp and noise.cpp
Removed unused variable from curvegradient.cpp
Add parentheses around '&&' operator in conditions
Comment unused variable in curvegradient.cpp
Fix float literals in mod_particle/random.cpp
Return strange code in curveset.cpp and comment it
Remove unused variables from sinfig-stodio code
Fix condition (replace & to &&) in gui/preview.cpp